#include <stdio.h>

int lower(int c);

int main()
{
    printf("out1 = %c\n", lower('H'));
    printf("out2 = %c\n", lower('b'));
    return 0;
}

int lower(int c)
{
    return (c >= 'A' && c <= 'Z') ? (c + 'a' - 'A') : c;
}